The objective of this research is to establish an animal model for chronic respiratory disease to be used in air pollution studies. Chronic respiratory disease (CRD) in mice will be established by respiratory challenge with Mycoplasma pulmonis, strain M. After the mortality rate has been determined in the initial acute phase of the disease, the chronic infection will be studied using the following parameters: concentration of mycoplasma in the lungs and middle ear; lung edema, histopathology of lungs, tracheas, and nasal cavities using light and scanning electron microscopy; circulating antibody; serum immunoglobulin levels; and cell-mediated immunity. Mice will be subjected to single and multiple exposures of concentrations of ozone (O3), nitrogen dioxide (NO2), and O3/NO2 mixtures that have been shown to increase susceptibility of mice to acute respiratory infection. CRD in pollutant-exposed and air-control mice will be compared using the above mentioned parameters. The results will be correlated with previously established effects of these pollutants on healthy animals and animals with acute pneumonia.